US2122132A - Refractory brick or radiant for surface combustion burners - Google Patents

Description

A. DOCKING June 28, 1938.

REFRACTORY BRICK OR RADIANT FOR SURFACE COMBUSTION BURNERS Filed Nov. 17, 1936 Patented June 28, 1938 UNITED STATES REFRACTORY BRICK OR RADIANT FOR SURFACE COMEBUSTION BURNERS Arthur Docking, Sanderstead, England Application November 17, 1936, Serial No. 111,224 In Great Britain November 27, 1935 4 Claims.

This invention relates to improvements in and relating to refractory bricks or radiants for use in the surface combustion of a combustible mixture of gas and air.

The type of burner to which the present invention is applicable comprises a cast iron box containing a cover of refractory brick under which is an air and gas mixing chamber.

The present invention comprises a surface combustion burner of the type specified, wherein the refractory brick is provided with a series of holes of which the lower portion of each hole is continued as a series of smaller holes leading from the air and gas mixing chamber.

The brick may be provided with holes of about inch diameter to a depth of about 2 to 3 inches opening out to to 1 inch diameter and to a further depth of about 4 to 5 inches.

The refractory brick is cemented into the opening of a cast iron box to form a gas tight joint, space being provided between the back of the brick and the bottom of the cast iron box to allow of means for admitting and the mixing of the air and gas, and the free entry of the mixture to the small holes in the refractory brick.

The invention is illustrated by the accompanying drawing in which Figure 1 is a sectional view of the burner and Figure 2 is a plan of the same.

In this drawing 2 is the cast iron box, 3 the refractory brick, 4 the large holes therein, 5 the china clay plugs, 6 the small holes in the plugs.

Air is introduced through an inlet 1 and passes through a restricted passage 8 in the air and gas mixing tube 9 conveying the air and. gas over a spreader H] to the mixing and distributing chamber below refractory brick 4 and from thence to entrance to the small holes 5.

The gas is admitted through a side passage H leading to a chamber I2 surrounding the restricted portion 8 of the air inlet 1.

The refractory brick 3 is fixed in the box 2 by cement 13.

The gas and air mixture finds its way preferably under pressure through the small holes 6 and burns as a kind of Bunsen flame causing the surface of the brick to become incandescent without visible sign of flame. In the usual type of burner the holes through which the gas and air mixture pass are too large to prevent backfire if the pressure falls so that the velocity of the gas and air mixture is below the rate of back-fire. This is an objectionable feature as if the gas and air mixture is checked to lower the temperature back-firing occurs.

According to the present invention this objection is overcome by using holes of a smaller diameter. It is well known that holes of less than 's inch diameter offer such a cooling effect to the gas and air mixture that no back-firing occurs no matter what drop occurs in the pressure of the gas and air mixture. With the present method of manufacturing firebrick it is not commercially possible to core holes of such small diameters and my invention provides for tubes made of china clay or any suitable refractory material cored with holes to the desired diameter. These tubes are extruded and no difficulty is experienced in their manufacture. These tubes are cemented into holes, provided in the bricks, to form a gas-tight joint, and. are about 1 inch to 2 inches deep, opening out to holes of about to 1 inch diameter which depth prevents the heat from the radiant surface of the brick receding to the gas chamber thereby causing a backfire and also offers a sufiicient cooling depth for the gas and air mixture. Another important feature of my invention is that the small diameter of these holes through which the gas and air mixture issues greatly minimizes combustion noise which is objectionable when refractory bricks or radiants are used as heating elements for space heating.

The apparatus made in accordance with this invention is applicable for use with low pressure gas and air blast and to high pressure gas and air plant, and to produce a face temperature up to 1400 C.

The refractory bricks may be made in two horizontal portions cemented together, the lower one containing the china clay tubes which may have from one to nine holes or more.

The small holes may be about 1 millimetre in diameter and about 45 millimetres deep and the larger holes about 8 millimetres in diameter and of a depth to make the brick 4 to 8 inches thick.

What I claim and desire to secure by Letters Patent is:

1. In a surface combustion burner, means forming a mixing and distributing chamber, a block of refractory material having a plurality of passages extending therethrough from face to face thereof, and a plurality of elongated plugs of refractory material each formed with a plurality of longitudinally extending holes of a diameter sufiiciently small to prevent back flashing to said mixing and distributing chamber, and each secured in one of said passages adjacent said mixing and distributing chamber.

2. In a surface combustion burner, means forming a mixing and distributing chamber, a

fire-brick block having a plurality of elongated cylindrical passages extending therethrough from face to face thereof, and a plurality of elongated cylindrical, china clay plugs each formed with a plurality of longitudinally extending holes of a diameter sufiiciently small to prevent back flashing to said mixing and distributing chamber, and each cemented in one of said passages adjacent said mixing and distributing chamber.

3. In a surface combustion burner, means forming a mixing and distributing chamber, a

block of firebrick formed with a plurality of pas sages extending therethrough, and each comprising a narrow portion adjacent the face of said block presented toward said mixing and distributing chamber and a Wider portion adjacent the opposite face of said block, and a plurality of elongated china clay plugs filling said narrow portions of said passages, and each formed with a plurality of fine longitudinally extending holes of sufficiently small diameter to prevent back flashing to said mixing and distributing chamber.

4. In a surface combustion burner, means forming a mixing and distributing chamber, a block of refractory material having one face thereof recessed to form a combustion chamber, and having a plurality of elongated cylindrical passages communicating at one end With said combustion chamber, and at the other end with said mixing and distributing chamber, and a plurality of elongated cylindrical, china clay plugs each cored with a plurality of longitudinally extending holes of a diameter sufficiently small to prevent back flashing from said combustion chamber to said mixing and distributing chamber,

- and each cemented in one of said passages in said block so as to fill said passage.

ARTHUR DOCKING.

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